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# Copyright 2014 - 2016 OpenMarket Ltd
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import logging
from typing import TYPE_CHECKING, Optional
import synapse.types
from synapse.api.constants import EventTypes, Membership
from synapse.api.ratelimiting import Ratelimiter
from synapse.types import UserID
if TYPE_CHECKING:
from synapse.server import HomeServer
logger = logging.getLogger(__name__)
class BaseHandler:
"""
Common base class for the event handlers.
Deprecated: new code should not use this. Instead, Handler classes should define the
fields they actually need. The utility methods should either be factored out to
standalone helper functions, or to different Handler classes.
"""
def __init__(self, hs: "HomeServer"):
self.store = hs.get_datastore()
self.auth = hs.get_auth()
self.notifier = hs.get_notifier()
self.state_handler = hs.get_state_handler()
self.distributor = hs.get_distributor()
self.clock = hs.get_clock()
self.hs = hs
# The rate_hz and burst_count are overridden on a per-user basis
self.request_ratelimiter = Ratelimiter(
store=self.store, clock=self.clock, rate_hz=0, burst_count=0
)
self._rc_message = self.hs.config.rc_message
# Check whether ratelimiting room admin message redaction is enabled
# by the presence of rate limits in the config
if self.hs.config.rc_admin_redaction:
self.admin_redaction_ratelimiter: Optional[Ratelimiter] = Ratelimiter(
store=self.store,
clock=self.clock,
rate_hz=self.hs.config.rc_admin_redaction.per_second,
burst_count=self.hs.config.rc_admin_redaction.burst_count,
)
else:
self.admin_redaction_ratelimiter = None
self.server_name = hs.hostname
self.event_builder_factory = hs.get_event_builder_factory()
async def ratelimit(self, requester, update=True, is_admin_redaction=False):
"""Ratelimits requests.
Args:
requester (Requester)
update (bool): Whether to record that a request is being processed.
Set to False when doing multiple checks for one request (e.g.
to check up front if we would reject the request), and set to
True for the last call for a given request.
is_admin_redaction (bool): Whether this is a room admin/moderator
redacting an event. If so then we may apply different
ratelimits depending on config.
Raises:
LimitExceededError if the request should be ratelimited
"""
user_id = requester.user.to_string()
# The AS user itself is never rate limited.
app_service = self.store.get_app_service_by_user_id(user_id)
if app_service is not None:
return # do not ratelimit app service senders
messages_per_second = self._rc_message.per_second
burst_count = self._rc_message.burst_count
# Check if there is a per user override in the DB.
override = await self.store.get_ratelimit_for_user(user_id)
if override:
# If overridden with a null Hz then ratelimiting has been entirely
# disabled for the user
if not override.messages_per_second:
return
messages_per_second = override.messages_per_second
burst_count = override.burst_count
if is_admin_redaction and self.admin_redaction_ratelimiter:
# If we have separate config for admin redactions, use a separate
# ratelimiter as to not have user_ids clash
await self.admin_redaction_ratelimiter.ratelimit(requester, update=update)
else:
# Override rate and burst count per-user
await self.request_ratelimiter.ratelimit(
requester,
rate_hz=messages_per_second,
burst_count=burst_count,
update=update,
)
async def maybe_kick_guest_users(self, event, context=None):
# Technically this function invalidates current_state by changing it.
# Hopefully this isn't that important to the caller.
if event.type == EventTypes.GuestAccess:
guest_access = event.content.get("guest_access", "forbidden")
if guest_access != "can_join":
if context:
current_state_ids = await context.get_current_state_ids()
current_state_dict = await self.store.get_events(
list(current_state_ids.values())
)
current_state = list(current_state_dict.values())
else:
current_state_map = await self.state_handler.get_current_state(
event.room_id
)
current_state = list(current_state_map.values())
logger.info("maybe_kick_guest_users %r", current_state)
await self.kick_guest_users(current_state)
async def kick_guest_users(self, current_state):
for member_event in current_state:
try:
if member_event.type != EventTypes.Member:
continue
target_user = UserID.from_string(member_event.state_key)
if not self.hs.is_mine(target_user):
continue
if member_event.content["membership"] not in {
Membership.JOIN,
Membership.INVITE,
}:
continue
if (
"kind" not in member_event.content
or member_event.content["kind"] != "guest"
):
continue
# We make the user choose to leave, rather than have the
# event-sender kick them. This is partially because we don't
# need to worry about power levels, and partially because guest
# users are a concept which doesn't hugely work over federation,
# and having homeservers have their own users leave keeps more
# of that decision-making and control local to the guest-having
# homeserver.
requester = synapse.types.create_requester(
target_user, is_guest=True, authenticated_entity=self.server_name
)
handler = self.hs.get_room_member_handler()
await handler.update_membership(
requester,
target_user,
member_event.room_id,
"leave",
ratelimit=False,
require_consent=False,
)
except Exception as e:
logger.exception("Error kicking guest user: %s" % (e,))
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